Cytoembryology of some Malaysian dipterocarps, with some evidence of apomixis

KAUR, A., JONG, K., SANDS, V. E. & SOEPADMO, E., 1986. Cytoembryology of some Malaysian dipterocarps, with some evidence of apomixis. Embryological and cytological studies on some members of the Dipterocarpaceae were undertaken. Of the dipterocarps investigated 83% were diploids. Two new polyploids were observed, namely Shorea resinosa (2 n = 3x = 21) and Hopea subalata (2 n = 3x = 21). Multiple seedlings were observed in H. subalata, Shorea agami, S. argentifolia, S. ovalis, S. pauciflora and S. resinosa. For the first time embryological studies have conclusively demonstrated reproduction by agamospermy in 5. ovalis and S. agami. Considerable evidence leads to the inference that H. subalata, S. resinosa and 5. macroptera are also agamosperms. Each of these produces multiple seedlings. Of these apomictic species three are polyploids, namely S. ovalis (2 n = 4x = 28), H. subalata (2 n = 3x = 21) and S. resinosa (2 n = 3x = 21), whereas S. agami (2 n = 14) and S. macroptera (2 n = 14) are diploids.     

Fungi associated with the aerial parts of Malaysian mangrove plants

The leaf surface fungi associated with nine species of mangrove plants includingAvicennia alba, A. officinalis, Bruguiera parviflora, Ceriops tagal, Rhizophora apiculata, R. mucronata, Sesuvium portulacastrum, Sonneratia alba, andXylocarpus mollucensis were studied using direct observation techniques and leaf washings. Over 40 fungal taxa were isolated from the leaf washings. Of these, species ofAspergillus, Choanephora, Cladosporium, Curvularia, Fusarium, Nigrospora, Penicillium, Pestalotiopsis, Trichoderma, andZygosporium were frequently encountered in the washings of all nine mangrove plants. Fewer species of fungi includingCladosporium oxysporum, Corynespora cassiicola, Fusarium, Penicillium, Pestalotiopsis, andZygosporium were capable of growth on the washed leaves. The major phylloplane fungus on plants with higher leaf tannin content (e.g.B. parviflora, C. tagal, Rhizophora spp., andX. mollucensis) wasPestalotiopsis. Leaves with relatively lower amounts of tannin supported the proliferation ofFusarium as the major fungus. Fungi were present on the plumule and cotyledonous sheath even before the leaves opened.Pestalotiopsis persisted throughout the development and growth of the leaves. Many of the fungi encountered on senescent leaves have been reported in earlier studies to be the primary colonisers of submerged decaying leaves.     

Anthocyanins of some Malaysian members of the gesneriaceae

The occurrence of 'normal' 3-hydroxylated anthocyanins in 8 Malaysian species of the Gesneriaceae supports the important chemotaxonomic results for this family. New compounds found in Chirita, Didissandra and Didymocarpus are the 3-arabinosylglucoside-5-glucosides of cyanidin and malidin, pigments which may have some systematic value.     

Fungi associated with the aerial parts of Malaysian mangrove plants

The leaf surface fungi associated with nine species of mangrove plants includingAvicennia alba, A. officinalis, Bruguiera parviflora, Ceriops tagal, Rhizophora apiculata, R. mucronata, Sesuvium portulacastrum, Sonneratia alba, andXylocarpus mollucensis were studied using direct observation techniques and leaf washings. Over 40 fungal taxa were isolated from the leaf washings. Of these, species ofAspergillus, Choanephora, Cladosporium, Curvularia, Fusarium, Nigrospora, Penicillium, Pestalotiopsis, Trichoderma, andZygosporium were frequently encountered in the washings of all nine mangrove plants. Fewer species of fungi includingCladosporium oxysporum, Corynespora cassiicola, Fusarium, Penicillium, Pestalotiopsis, andZygosporium were capable of growth on the washed leaves. The major phylloplane fungus on plants with higher leaf tannin content (e.g.B. parviflora, C. tagal, Rhizophora spp., andX. mollucensis) wasPestalotiopsis. Leaves with relatively lower amounts of tannin supported the proliferation ofFusarium as the major fungus. Fungi were present on the plumule and cotyledonous sheath even before the leaves opened.Pestalotiopsis persisted throughout the development and growth of the leaves. Many of the fungi encountered on senescent leaves have been reported in earlier studies to be the primary colonisers of submerged decaying leaves.     

Novel features of retroviruses associated with human diseases.

The last decade has witnessed a new chapter in the history of retrovirology. As of now, four human retroviruses have been identified and molecularly characterized. They are associated with a wide spectrum of human diseases including cancer, immunodeficiency and neurological disorders. By virtue of their clinical relevance, their novel genes and regulatory mechanisms these viruses have become the focal point of research in retrovirology. The study of these viruses is of fundamental importance in understanding the mechanisms leading to transformation of human cells and distortion of the immunological state.     

Exogenous markers for the characterization of human diseases associated with oxidative stress

Many human conditions, including neurological diseases, atherosclerosis, cancer, diabetic complications and aging, are thought to be associated with oxidative stress (OS). The development of reliable and informative markers for the characterization of OS in humans is thus highly important. Various endogenous markers are known, but their accumulation with increasing OS and with time is not certain, and most of them do not provide information on the type or source of the stress, or on the kinetics of their formation. The aim of the present overview is to present exogenous markers, designed and synthesized by our group, which are sensitive to OS and can identify its presence, the type of reactive oxygen and nitrogen species involved ex vivo, and potential damage incurred by bio-macromolecules, in real time. A microdialysis technique is used in animals for evaluation of OS in vivo. The designed probes are composed of several endogenous subunits, attached together covalently to form molecules that do not exist as such in humans. The subunits include an amino acid (tyrosine), an unsaturated fatty acid (linoleic acid), a nucleic acid (2′-deoxyribose guanosine) and cholesterol, representing the major macromolecules of the body, i.e. proteins, lipids, DNA and sterols, respectively. Incubation of these markers in a biological sample ex vivo, such as blood/serum, urine, saliva, cells or tissues under OS, alters their subunits, which are then analyzed and identified by LC/MS. This review demonstrates the potential of these markers to identify OS in samples taken from humans and animals suffering from, for example, atherosclerosis, hypertension, or Alzheimer's or Parkinson's disease.     

Cytotoxicity of adherent cells associated with some human tumours and lung tissues

Summary Cells were isolated by adherence from human tumours, and the majority of them showed the capacity to phagocytose latex particles, incorporate neutral red, and form rosettes with antibody-coated ox erythrocytes, and were positive for nonspecific esterase activity. The monolayers lyse antibody-coated human erythrocytes at low effector: target ratios. In 17 of 25 cases cytotoxicity for autologous tumour cells was apparent in an 18-h ⁵¹Cr release assay. Cytotoxicity was dose-dependent and nonspecific for tumour targets, but cells isolated from tumour-free lung areas appeared to be resistant to damage. Adherent cells from tumour-free lung areas also killed autologous tumour targets but not normal lung cells. The problems of the interpretation of these data are discussed.     

The role of homocysteine thiolactone in some of human diseases

In the present article we discuss the most recent data regarding the role of homocysteine, its cyclic thioester--homocysteine thiolactone and the process of protein N-homocysteinylation in human disease. The protective role of thiolactonase/paraoxonase enzyme, carried on high density lipoproteins (HDL) in human blood, as well as the influence of structural modifications on HDL function are discussed. We also describe the effect of vitamin therapy (folic acid, vitamins: B6, B12) used for lowering the homocysteine level in humans as well.     

An ancient evolutionary origin of genes associated with human genetic diseases

Several thousand genes in the human genome have been linked to a heritable genetic disease. The majority of these appear to be nonessential genes (i.e., are not embryonically lethal when inactivated), and one could therefore speculate that they are late additions in the evolutionary lineage toward humans. Contrary to this expectation, we find that they are in fact significantly overrepresented among the genes that have emerged during the early evolution of the metazoa. Using a phylostratigraphic approach, we have studied the evolutionary emergence of such genes at 19 phylogenetic levels. The majority of disease genes was already present in the eukaryotic ancestor, and the second largest number has arisen around the time of evolution of multicellularity. Conversely, genes specific to the mammalian lineage are highly underrepresented. Hence, genes involved in genetic diseases are not simply a random subset of all genes in the genome but are biased toward ancient genes.     

Mitochondrial abnormalities in some human muscular diseases and in experimental ischemic myopathy

Morphologic abnormalities have been observed in two cases of human polymyositis and in three cases of ocular myopathies. Similar findings can be observed in experimental ischemic myopathy. "Ragged red" fibres, with anomalous distribution of oxidative enzymes, mitochondrial alterations, with presence of intracristal paracrystalline inclusions and degenerative myofibrillar changes are the similar features. The similarity between some of these alterations, expecially mitochondrial changes, is remarkable, but it is difficult to correlate them to the primary etiology of described human myopathies.     

Improvement of the nutritional value of rye products by solid-state fermentation with fusaria

The use of some cereals in animal nutrition, e.g. rye, is limited because of some constituents. By solid-state fermentation using selected Fusaria it is possible to enhance the nutrition value and to enrich the fermented material with free and essential amino acids and vitamins. The fermentation method is described and the results of analytical assays are discussed.     

Role of garlic (Allium sativum L.) in human and plant diseases

A resurgence of interest in garlic due to recent revelations of its beneficial effects in the treatment of various human and plant diseases and also due to validation of claims made in traditional systems of medicine has resulted a plethora of publications on different aspects of garlic in recent years. Chemical constituents of garlic and their variations on the methods of isolation have been discussed in the present review. Effect of garlic and its constituents against various human and plant pathogenic and saprophytic microorganisms has also been reviewed.     

Patterns of ferns community assemblages in some Malaysian and Nigerian tropical forests

Research on fern ecology has gained attention in the last decade, yet there is a paucity of information on the comparison of ferns communities across continents. This study focused on comparing the ferns community assemblages in some tropical forests of Malaysia and Nigeria, thereby assessing the patterns of species richness (SR) and phylogenetic diversity (PD) in relation to the bioclimatic drivers across the continents. The diversity and taxonomic compositions of ferns were assessed using 180 plots of 10 m × 10 m in each country. The species richness and other diversity indices were determined using the combined forests data for each country and for the individual forests. Also, the phylogenetic diversity of the ferns was assessed using the genus‐based molecular sequences downloaded from the GeneBank. The patterns of the ferns SR and PD in the two countries as driven by some bioclimatic factors were evaluated using the regression analysis. The observed and rarefied–extrapolated fern species richness is significantly higher in Malaysian forests than in Nigerian forests. Also, the other diversity indices are significantly higher in Malaysian forests except for the Shannon index which showed no significant difference between the two biogeographic regions. There is a very low similarity (7.41%) in the taxonomic composition of ferns between the two biogeographic areas, although the similarity in composition increased with increasing taxonomic levels (species: 7.41%, genus: 12.77%, family: 70.96%). Terrestrial and epiphytic ferns are more dominant than the other life forms in the two countries. The precipitation variables drive the phylogenetic structure of ferns in Nigeria, whereas both precipitation and temperature variables drive the phylogenetic structure of ferns in Malaysia. This indicates that ferns assemblages in Nigeria and Malaysia are driven by both climatic variables. Besides, we also hypothesize that these observed differences could be due to other historical and evolutionary processes.